The Turkish military has returned fire after another mortar shot from Syria landed in countryside in southern Turkey, local officials said.

"A mortar landed today (Saturday) at 7:00am (local time) about 50 metres inside Turkish territory in an open space about 700 metres from the village of Guvecci and about 300 metres from a police station," the governor's office of the border province of Hatay said in a statement.

No casualties were reported, it added.

The Turkish army responded by firing four rounds of mortars, the statement said, adding that the Syrian fire had come from loyalists who were firing at rebels near the Syrian-Turkish border.

"We are not interested in war, but we're not far from it either," Mr Erdogan said.

"Those who attempt to test Turkey's deterrence, its decisiveness, its capacity - I say here they are making a fatal mistake.

"When they say 'if you want peace prepare for war' it means that when the time comes, war becomes the key to peace".

The warning came a day after his government obtained a one-year mandate from parliament authorising military raids into Syria if necessary.

Wednesday's incident marked the first time Syrian shells killed Turkish nationals since the uprising against the regime in Damascus began in March 2011.

Damascus has said the mortars landed in Turkey accidentally.

The UN Security Council issued a toughly worded statement condemning Syria's initial shelling, although it was a rung down from a formal resolution.

It said the shelling "highlighted the grave impact the crisis in Syria has on the security of its neighbours and on regional peace," and "demanded that such violations of international law stop immediately and are not repeated."